i had a question. hope to have some advise.
i now doing a school project then would require a digital camera.
in short i just need to capture a very sharp image of the size of an A4 paper. i don`t need to print it out. just to store it into the computer.

so my question is:
without using the optical or digital zoom.
is there any difference between taking the image(A4 size) with a 2M or 3M pixels digital camera??

I find it difficult to interpret your question but let's give it a shot.

You have an A4 sized image, which you want to "grab". You could do that using a scanner but instead you would like to use a digital camera for that.

I do not understand your comment with regard to the zoom bit. To get the highest quality grab, you want the picture frame of your camera to be fully filled with the image that you want to grab. How you do that (whether to move your camera by hand or optical zoom) does not matter. Do not use digital zoom though (explanation follows).

The (obvious) difference between using the 2M or 3M camera will be the amount of pixels in your image. It is to be expected that more pixels will give a higher quality (better resolution) grab (just like you have scanners with different resolutions). the M stands for mega, so you expect to get 2 000 000 pixels with the 2M camera, and a 1 000 000 more with the 3M camera, which is substantially more (thus better).

Do not use digital zoom because it will reduce the number of effectively used pixels of the camera CCD.